The present invention relates to an improved transmission with built-in brake, particularly for vehicles.
Electric power units are usually used in vehicles for indoor transport, such as for example fork-lift trucks; each one of these drive units, coupled to a transmission, forms a propulsion unit.
The transmission disclosed in U.S. Ser. No. 08/131,244 of Oct. 4, 1993, is known among transmissions adapted for these propulsion units.
This transmission includes, in an oil-bath casing, an epicyclic reduction unit that is kinematically connected to the power unit by means of two gears, the driven gear being axially fixed, coaxial to the sun gear and associated therewith by means of a splined coupling.
A disk brake is arranged between the epicyclic reduction unit and the driven gear and has disks that are alternately rigidly coupled so as to rotate together with the former or with the latter.
The disk brake is associated with a pusher that is connected by means of axial pins that pass through the driven gear in adapted holes thereof and are associated with a pusher flange from which a pivot extends; said pivot protrudes from the casing, and thrust applying means act thereon.
These actuation means, disclosed in Italian patent application PD 92 A 000177 of Oct. 19, 1992, comprise a first-class lever that is pivoted on the lid of the containment casing and acts with a first arm on the pusher pivot protruding from said casing.
The lever acts with a second arm on the piston of a fluid-activated cylinder whose body is monolithic with the lid.
In the practical embodiment of the above described transmission it has been observed that, although it solves several drawbacks of previous solutions, it is still not optimum from the point of view of constructive simplicity and therefore of operating reliability.
In this transmission, particularly in the part related to the actuation of the disk brake, there is a large number of moving parts and therefore of parts subject to wear.
Furthermore, the actuation lever moves both when the fluid-activated cylinder is operated (braking during normal use) and when acting on said lever by means of a cable-operated control (parking brake).
The lever is also subjected to very intense forces to pack the disks.